During the drilling, completion and operation of oil, gas and water wells many occasions arise when tubular goods or lines must be run into and/or pulled from the bore hole. Usually such tubular goods are made from steel and being much denser than the fluid into which they are run require large and expensive handling equipment. U.S. Pat. No. 4,024,913 to Donovan B. Grable relates to the use of high strength, non-metallic lines and tubulars having a specific gravity less than 2.0 and tensile strengths greater than 185,000 psi.
Also, it is well known in oil and gas drilling operations to float heavy strings of casing into a bore hole to reduce hoisting load. In this operation a lower section of casing is plugged to prevent fluid entry thus providing the required buoyancy. However, the combination of sections of two or more tubular goods or rods having different densities to form a complete string the composite density of which along its length being essentially equal to the density of the well liquid, and thus not requiring the use of heavy hoisting equipment to run into and to take out of a well, appears to be novel.